I agree with both posters before me. Though I personally wouldn't expect differences in sound between optical and coax, it seems many prefer coax as the digital connection (maybe someone can explain), but I also heard that optical is more stable for longer distances.

If you have a receiver with a built-in DAC and these inputs, try all three methods and choose your favorite to listen to.

I generally have found coaxial digital cables to sound a bit better than most optical cables, though I do have glass optical cables that sound better than the plastic optical cables, and rival the coaxial.

I agree with both posters before me. Though I personally wouldn't expect differences in sound between optical and coax, it seems many prefer coax as the digital connection (maybe someone can explain), but I also heard that optical is more stable for longer distances.

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There really isn't any difference from a performance perspective.

I prefer coax for cost and reliability reasons. Fiber has the theoretical advantage over extremely long distances because it is inherently immune to noise, however getting good fiber that long can be pricey. And SPDIF is a rather low-bandwidth digital signal, and any decent 75ohm coax should be plenty good for that up to really hundreds of feet realistically. I have never run into a coax SPDIF failure. And coax is much sturdier, the connector doesn't fall out, it won't crack or split or break like fiber, and it's easily terminated in the field by anyone.

I use both personally where for instance my Mac has toslink out and I go about 40 feet with that no problem, but in systems I've installed, I always preferred coax wherever possible, particularly for longer runs for these various reasons. I've replaced far too many shattered and crushed optical cables. Coax is the tried-and-true, and cheap.

I just posted about this in another thread, and it seems appropriate to quote myself here. I initially resisted getting into this thread as it didn't seem sensible to open up such a debate in the context of a cd player and "receiver", which probably implies insufficient system-wide resolution for any of this to really matter much...

I have Been There, Done That with plenty of expensive (four figure) digital cables.

The reasons the expensive cables all sound different is that they all accentuate different problems with S/PDIF.

S/PDIF works best with BNC-terminated solid-core RG6 coax. Period. A digital engineer whom I have the utmost respect for recommended 10' as a good length to compromise between signal loss/interference and minimizing issues caused by reflections in the transmission line. I played with cables in lengths from extremely short, up through the popular 1M and 1.5M and up to 25' and found 7-15' to be the sweet spot, depending on the associated gear and how much it drifts from proper S/PDIF spec...everything seems to.

Until you have heard S/PDIF this way, you have not heard S/PDIF. The difference between a kilobuck XLR or RCA digital cable and a cable which is actually suited to this format is CLEARLY noticeable. Nevermind Toslink...

Toslink is wrought with problems... I'd recommend avoiding it. If I had to run a length of Toslink, I'd go for Blue Jeans Cable's Mitsubishi ESKA stuff, and keep the length as short as is humanly possible.

Ideally, if cost is no object, you'd pay someone to lop off the Toslink transmitters/receivers on your gear and put in properly terminated and transformer isolated BNC connections.

ST optical cables (these showed up in the high end in the 90s--Wadia was particularly into them) did a much better job, and the expensive Aural Symphonics ST cable produced excellent results...

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Consider also that optical transmission subjects fragile S/PDIF to two unnecessary "media conversions", as it starts as an electrical signal at the source and finishes as an electrical signal after the receiving Toslink jack.

S/PDIF has much more in common with video signals than analogue audio... perhaps that is why audiophile cable companies appear to be completely incapable of designing an appropriate cable. Also note how heavily BNC connections are employed in commercial video applications...

To address The Hud's commend re optical being "faster", "speed" as you are thinking of it doesn't really come into the equation. In fact, due to the low quality of generally-available Toslink transmitters and receivers, coax is generally preferable for higher-"speed" (i.e. higher sampling rate) applications.

As for stability over length, you really need to take environmental effects into account. Perhaps if you're in a room with tons of interference in the appropriate band, optical might beat coaxial... but professionals tend to go AES/EBU over XLR at this point.

I can't really tell if you are being sarcastic, but in case you aren't (or anyone reading is curious), we're talking large percentages of the speed of light in either medium (light on fiber, or electrical signal down copper). The time it takes for the sound to reach your ear from the speakers is billions and billions and bajillions of times slower than the signal speed in either situation. To say that the 'speed' of signal propagation between fiber and coax has no significance in this particular application is an understatement.

Signal speeds down cable can make a difference in many applications, but usually that's over extremely long distances with a single cable, or more often, when using multiple cables (or multiconductor cables) where time alignment is critical. This is not such an application: just one signal down one cable, the difference between 65% and 70% the speed of light, say, (or whatever) is beyond immaterial.

...optical transmission subjects fragile S/PDIF to two unnecessary "media conversions", as it starts as an electrical signal at the source and finishes as an electrical signal after the receiving Toslink jack.

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The chips involved here spit out an electrical signal, which the sending optical jack converts to light, the receiving optical jack converts back to electrical, and the receiving chip finally gets the electrical signal. To further illustrate the point, you can literally remove a Toslink optical jack from the circuit board, solider on a jack for a coax cable, and it'll work.

With my very old DAC (1990s John Westlake designed Dacmagic) I have a choice of optical and coaxial via a front panel knob.

There is definitely a difference (Westlake himself preferred the optical) - the optical sounds less etched / bright than the coaxial. I use this as a form of tone control - if the recording is a bit bright I use the optical - if it is dull sounding I go for the coaxial.

I have read that coaxial connections are susecptible to radio frequency interference (RFI) and electro-magnetic interference (EMI), creating hum. Might this type of intereference be created if a coaxial cable is used near a Wi-Fi connection for an A/V receiver?

I have read that coaxial connections are susecptible to radio frequency interference (RFI) and electro-magnetic interference (EMI), creating hum. Might this type of intereference be created if a coaxial cable is used near a Wi-Fi connection for an A/V receiver?

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The interference would not sound like hum, at least into an analog interface. On a digital interface this would not really be much a concern, plus if you're using decent coax it's very heavily shielded. However, it is true that optical is inherently immune to any such interference.

There's one thing that I always try to point out in these types of threads if nobody beats me to it: On many modern receivers, the analog inputs are redigitized and passed through the internal DAC if you use any type of DSP, Room Correction, Bass Management (for "small" speakers), Phase Matching, etc. What's almost always left out of the documentation, though, is the resolution/frequency of the A to D conversion.

So if you're not using your receiver's version of "Direct Mode" or "Pure Mode" or whatever they happen to call it, then the signal is more than likely going through the receiver's internal DAC anyway and any analog inputs might be going through one extra a/d d/a step. Whether that is audible or not is debatable.